This invention relates to an improved dry toner formulation as used in Xerography and originally developed for the toner cartridge remanufacturing industry. This includes copiers, laser printers, facsimile machines and microfiche printers.
CANON has designed an all-in-one cartridge as seen in Pat. No. 4,975,744, issued Dec. 4, 1990 and assigned to CANON. Several companies have used these cartridges in laser printers, copy machines and facsimile machines, each with the varying printer engines and a different nameplate. Originally, these cartridges were designed to be "disposable". However, after the first all-in-one toner cartridge was introduced, it did not take long before laser cartridge remanufacturers such as myself began remanufacturing these cartridges. These "disposable" cartridges were designed to function for only one cartridge cycle without remanufacturing. The remanufacturers has found certain components that needed replacement on a regular basis. In 1990, the first aftermarket photoreceptor drum became available for use in remanufacturing the all-in-one cartridge of the "SX" engine variety, the most popular printer cartridge from around 1987 through 1994. When the long-life photoreceptor drum became available, the entire remanufacturing industry turned around and gained great strength and began a huge growth surge that still continues. In October 1993, HEWLETT-PACKARD, the largest seller of this printer engine using the all-in-one cartridge, entered the cartridge remanufacturing industry with the "Optiva" cartridge, further increasing the size as well as credibility of this relatively new industry. However, this relatively new industry grew from the all-in-one cartridge shortly after its debut. Before the introduction of the long-life drum, sometimes called the "superdrum" or "duradrum", the SX cartridge would last for around three cartridge remanufacturing cycles at best, since the actual useful life of the OEM drum was three cycles. However, the long-life drums got their names from the fact that they were designed to last for many remanufacturing cycles or recharges as they are sometimes called. Typically, the long life drum can last for ten or more such cycles, unlike the typical OEM (Original Equipment Manufacturer) drum. With the additional developments of drum coatings, originally designed for OEM drums, the long-life drum may last for many additional cycles. Some coatings, in theory, were designed to be dissolved and removed from over the drum surface every 1-3 cycles, so the drum life of the long-life drum almost seems limitless.
However, with photoreceptor drums lasting for many cycles, other components of the cartridge have a tendency to require greater durability, a better solution, or a greater life. Also, as the success of these cartridges has skyrocketed, the demand is for cartridges with longer cycles, so component improvements are significant. Therefore, avoiding natural problems with prevention means must also be implemented for cartridges of longer life both in longer cycle times and greater number of cycles. Dry toner powder is no exception. Many problems occur that cause premature failure. One example is ghosting (double imaging) caused by poor wiping of the photoreceptor drum with the wiper blade due to toner formulations in need of improvement. Another is ghosting caused at the (heat roller) fuser roller section because the fuser section no longer uses a fuser cleaner pad that oils it to prevent toner stick in the HP LX, NX, and EX printers. The OEM toner has components in the toner to help that the prior art aftermarket toners do not use to prevent toner stick to the heat fuser roller, usually TEFLON coated. One of the reasons for this problem is that toners with a relatively low melting point are required to function in a continuous high-speed application. Traditionally, this problem has been prevented by using a fuser roller cleaner wand with a felt pad that continuously cleans and oils the hot fuser roller as it turns. However, the practice of designing printers with self-oiling fuser cleaner pads has been abandoned by many OEM manufacturers. It is now expected that toners will function flawlessly without the self-oiling fuser roller cleaner pads.
Typically, there are different toner types. There are monocomponent type dry toners where the toner and developer are mixed together. Other compositions use multicomponent toners where the toner and developer are each separate powders. Many multicomponent toners also use carriers to help move the toner. The lubricant/flow agent of this invention may be applied to all toner, developer and toner-developer combinations, all kinds of dry toners.
Another problem is in the LX, BX and some other toner cartridges and the FX facsimile toner cartridge. When sealed with the aftermarket seals of which this applicant has three patents, (for example, U.S. Pat. No. 5,296,902, granted Mar. 22, 1994) the toner is driven horizontally with a paddle in the toner hopper through a narrow slot or passageway to the feed roller compartment. When the toner moves through this passageway, it may fill a portion of this narrow constriction and cause toner blockage resulting in a white streak on the output page before the toner cartridge is out of toner. In the past, some endusers have had success with the seal only later to find a toner blockage after using a different batch of toner with poor flow properties. Consequently, because of the described problems and similar problems experienced with applicant's patented shipping seals, applicant has developed a toner and a toner additive to solve the problem.
Other lubricants and flow agents have been used in the prior art. For example, zinc stearate has been used for years. Ground KYNAR powder has been used for quite some time. Among other finely ground powdered components used for this purpose in prior art are carnauba wax, colloidal silica and aluminum oxide.
In U.S. Pat. No. 4,395,485, Kashiwagi et al combine dry toner with a hydrophobic flow agent to maintain the flow of the toner in humid conditions. This agent would not lubricate the toner cartridge components.
Kurematsu et al, in their U.S. Pat. No. 4,748,474, suggest using TEFLON or similar lubricants in not less than 0.5 percent by weight with respect to the toner. U.S. Pat. No. 5,079,123 to Nanya et al discloses a dry-type toner which includes carnauba wax, substantially free of aliphatic acids, as a lubricant. The Background of the Nanya et al invention lists Japanese patents which add to dry toner such lubricants or releasants as silicone, varnish, fatty acids, higher alcohol, and other waxes.
U.S. Pat. No. 5,211,864 to Godlove is of interest for showing a slurry used to lubricate the cleaning blade in a printing machine. The slurry is a combination of a toner and a wax component and is applied to the blade prior to assembly and machine start-up. An electrophotographic toner composition disclosed by Kawasaki et al in U.S. Pat. No. 5,230,978 was developed for high speed and lower-heat copying machines. The composition uses various low-melt-viscosity and high-strength resins but, as best understood, does not contain a lubricant.